Mame4All was the first thing I tried when I got my Pi 2 and was very dissapointed with the bad sound. I’ve tried the same games on AdvanceMAME and the sound is good but I get screen tearing (no VSync ?). I’m using HDMI 1.4.
I saw a YouTube video somewhere that said SDL in RetroPie 3 was bugged and you had to reset the system to make the sound crackle go away, that doesn’t work for me. Like I said, AdvanceMAME using the same games (obviously different ROM versions) don’t have bad sound.